emf, internal resistance and combinations of cells — practice questions

Question 1 · difficulty L2 · understanding

When an external resistance of $5 \Omega$ is connected across terminals of a cell, a current of 0.25 A flows through it. When the $5 \Omega$ resistor is replaced by a $2 \Omega$ resistor, a current of 0.5 A flows through it. The internal resistance of the cell is $\_\_\_\_$ $\Omega$.

Question 2 · difficulty L2 · understanding

In an electrical circuit, a battery is connected to pass 20C of charge through it in a certain given time. The potential difference between two plates of the battery is maintained at 15V. The workdone by the battery is __________J.

Question 3 · difficulty L2 · understanding

The battery of a mobile phone is rated as $4.2 \mathrm{~V}, 5800 \mathrm{~mAh}$. How much energy is stored ir it when fully charged?

• A. 87.7 kJ
• B. 43.8 kJ
• C. 48.7 kJ
• D. 24.4 kJ

Question 4 · difficulty L2 · understanding

Given below are two statements : Statement-I : The equivalent emf of two nonideal batteries connected in parallel is smaller than either of the two emfs. Statement-II : The equivalent internal resistance of two nonideal batteries connected in parallel is smaller than the internal resistance of either of the two batteries. In the light of the above statements, choose the correct answer from the options given below.

• A. Statement-I is false but Statement-II is true
• B. Statement-I is true but Statement-II is false
• C. Both Statement-I and Statement-II are false
• D. Both Statement-I and Statement-II are true

Question 5 · difficulty L2 · understanding

In the given circuit, the terminal potential difference of the cell is :

• A. 3 V
• B. 4 V
• C. 2 V
• D. 1.5 V

Question 6 · difficulty L2 · understanding

The combination of two identical cells, whether connected in series or parallel combination provides the same current through an external resistance of 2$$\Omega$$. The value of internal resistance of each cell is

• A. 2$$\Omega$$
• B. 4$$\Omega$$
• C. 6$$\Omega$$
• D. 8$$\Omega$$

Question 7 · difficulty L2 · understanding

A cell E 1 of emf 6V and internal resistance 2$$\Omega$$ is connected with another cell E 2 of emf 4V and internal resistance 8$$\Omega$$ (as shown in the figure). The potential difference across points X and Y is :

• A. 10.0 V
• B. 2.0 V
• C. 5.6 V
• D. 3.6 V

Question 8 · difficulty L3 · understanding

Two cells of emfs 1 V and 2 V and internal resistance $2 \Omega$ and $1 \Omega$, respectively connected in parallel, gave a current of 1 A through an external resistance. If the polarity of one cell is reversed, then value of current through the external resistance will be $\frac{\alpha}{5} \mathrm{~A}$. The value of $\alpha$ is $\_\_\_\_$.

Question 9 · difficulty L3 · understanding

Two cells of emfs 1 V and 2 V and internal resistances $2 \Omega$ and $1 \Omega$, respectively, are connected in series with an external resistance of $6 \Omega$. The total current in the circuit is $I_1$. Now the same two cells in parallel configuration are connected to same external resistance. In this case, the total current drawn is $\mathrm{I}_2$. The value of $\left(\frac{\mathrm{I}_1}{\mathrm{I}_2}\right)$ is $\frac{x}{3}$. The value of $x$ is___________.

Question 10 · difficulty L3 · understanding

Two identical cells, when connected either in parallel or in series gives same current in an external resistance $$5 ~\Omega$$. The internal resistance of each cell will be ___________ $$\Omega$$.